Sahih Bukhari, Volume 4, Book56, Number 682

Narrated Ibn Mas’ud:
I heard a person reciting a (Quranic) Verse in a certain way, and I had heard the Prophet reciting the same Verse in a different way. So I took him to the Prophet and informed him of that but I noticed the sign of disapproval on his face, and then he said, “Both of you are correct, so don’t differ, for the nations before you differed, so they were destroyed.”
Sahih Bukhari, Volume 4, Book56, Number 682